Most of the database intensive applications are worring about the default
values of these variables obviously. Developers used to inform me that they need
to extend the wait_timeout value in order to complete
the query execution.
After some googling, it is found that default “wait_timeout”
value is good enough. We may need to reduce it to boost the server performance
which will helpful to minimize the “sleep” process loaded in memory. Increasing
number of sleeping process will reduces the server performance gradually. So
always keep the default value and make it reduce until the program/application
does not create any sleeping process which would helpful to improve the
performance noticeable. Slow_log_query is another
possible reason to have many sleeping process.
interactive_timeout : interactive time out for mysql
shell sessions in seconds like mysqldump or mysql command line
tools.
wait_timeout” : the amount of seconds during
inactivity that MySQL will wait before it will close a connection on a
non-interactive connection in seconds.
How to change the these variables
a. changing values at run time
Log in to the mysql
console and set the variable.
mysql> SET interactive_timeout=200;
Query OK, 0 rows affected (0.01 sec)mysql> SET GLOBAL interactive_timeout=200;
Query OK, 0 rows affected (0.00 sec)mysql> show variables like "%timeout%";
+----------------------------+-------+
| Variable_name | Value |
+----------------------------+-------+
| connect_timeout | 200 |
| delayed_insert_timeout | 300 |
| innodb_lock_wait_timeout | 50 |
| innodb_rollback_on_timeout | OFF |
| interactive_timeout | 200 |
| net_read_timeout | 200 |
| net_write_timeout | 200 |
| slave_net_timeout | 3600 |
| table_lock_wait_timeout | 50 |
| wait_timeout | 200 |
+----------------------------+-------+
10 rows in set (0.00 sec)
b. Using my.cnf : Add the following values in
/etc/my.cnf” and restart the mysql server.
[mysqld]
interactive_timeout=180
wait_timeout=180
Pls note that “wait_timeout” would be helpful to clear the
sleeping process as “interactive_timeout” does not make any
performance improvement since it affect the command line sessions. Obviously
increasing the values
of connect_timeout, net_read_timeout andnet_write_timeout would
help to skip the timeout errors when lengthy queries are being executed.
How to kill the MySQL Sleeping process
mysql> show full processlist;
+-------+------------+---------------------+---------------+---------+------+-------+-----------------------+
| Id | User | Host | db | Command | Time | State | Info |
+-------+------------+---------------------+---------------+---------+------+-------+-----------------------+
| 9435 | user | 192.168.10.15:52180 | db1 | Sleep | 26 | | NULL |
| 9943 | user | localhost:51179 | db2 | Sleep | 1 | | NULL |
| 9944 | user | localhost:54007 | db2 | Sleep | 29 | | NULL |
| 9947 | user | localhost:60638 | db2 | Sleep | 29 | | NULL |
| 10716 | root | localhost | NULL | Sleep | 5432 | | NULL |
| 10851 | root | localhost | NULL | Query | 0 | NULL | show full processlist |
+-------+------------+---------------------+---------------+---------+------+-------+-----------------------+
6 rows in set (0.00 sec)mysql> kill 9944;
Query OK, 0 rows affected (0.00 sec)mysql> show full processlist;
+-------+------------+---------------------+---------------+---------+------+-------+-----------------------+
| Id | User | Host | db | Command | Time | State | Info |
+-------+------------+---------------------+---------------+---------+------+-------+-----------------------+
| 9435 | user | 192.168.10.15:52180 | db1 | Sleep | 7 | | NULL |
| 9943 | user | localhost:51179 | db2 | Sleep | 9 | | NULL |
| 9947 | user | localhost:60638 | db2 | Sleep | 10 | | NULL |
| 10716 | root | localhost | NULL | Sleep | 5473 | | NULL |
| 10851 | root | localhost | NULL | Query | 0 | NULL | show full processlist |
| +-------+------------+---------------------+---------------+---------+------+-------+-----------------------+
7 rows in set (0.01 sec)
mysql>
On thread startup, the session wait_timeout value is initialized from the
global wait_timeout value or from the
global interactive_timeout value, depending on
the type of client (as defined by the CLIENT_INTERACTIVEconnect option to mysql_real_connect()).
参考：
http://www.serveridol.com/2012/04/13/mysql-interactive_timeout-vs-wait_timeout/
http://dev.mysql.com/doc/refman/5.5/en/server-system-variables.html#sysvar_wait_timeout
MySQL : interactive_timeout v/s wait_timeout,布布扣,bubuko.com